Head for powder spraying gun

ABSTRACT

A head for powder spraying guns having placed in front of the exit orifice a deflection part which deflects the stream by 180*.

United States Patent 1191 1111 3,811,620 Gebhardt May 21, 1974 HEAD FOR POWDER SPRAYING GUN 6] References Cited [75] Inventor: Otto R. Gebhardt, Fellbach, UNITED STATES PATENTS Germany 3,521,815 7/1970 Szasz 239/ 2,545,951 3/1951 Frese et al 239/499 X [73] Assgnee' F'rma Mueller KG 1,999,116 4/1935 Sidney 239/500 [22] Filed: NOV. 13, 1972 2,566,324 9/1951 Frese 23 /499 21 41114305734 1 pp 0 Primary Examiner-Lloyd L. King D Assistant ExaminerAndres' Kashnikow Foreign Appllcatlon P Data Attorney, Agent, 0r FirmMcGlew and Tuttie Dec. 20, 1971 Germany 2163111 52 us. c1 239/499, 239/504, 239/514, [571 ABSTRACT 239/515, 239/524 A head for powder spraying guns having placed in [51] Int. Cl B05b 1/26 front of the exit orifice a deflection part which de [58] Field Of Search 239/15, 499, 500, 504, fleets the stream by ll Claims, 4 Drawing Figures HEAD FOR POWDER SPRAYING GUN FIELD OF THE INVENTION The subject-matter of the invention is a head for powder spraying. guns such as used, for example, for coating workpieces with plastics powder or ceramic powder.

A variety of heads for powder spraying guns have already been suggested. They aim first of all to attain a favorable exit stream of a: powder-air mixture with a view to being able to coat the powder uniformly even on considerably articulated surfaces of workpieces.

In this connection it has already been suggested to place so called breaker plates in front of the exit orifice of powder spraying guns for the purpose of scattering, with a broad effect, the powder stream so that rather large surfaces can be powdered in a uniform way.

It has also been suggested to arrange the breaker plates in front of the exit tube of the powder spraying gun in such a manner that they are adjustable.

It has turned out, however, in practice that the breaker plates situated in the rectilinear powder-air stream are not able to influence the powder-air stream in the appropriate way for securing a uniform powder coating on the workpiece.

The present invention aims at suggesting a head for powder spraying guns which avoids the drawbacks of the devices known so far and which makes it possible to produce a uniform powder-air stream on the workpiece even in special form, for instance also as regards breadth.

SUMMARY OF THE INVENTION The present invention solves the problem in such a way that there is placed in front of the exit orifice of the powder-air gun a deflection part, for the powder-air stream, which deflects the stream by about 180 and that the deflected stream hits a breaker plate placed on the exit tube inwardly of the exit end, which deflects the stream, in its turn, in the direction of the workpiece.

On the one hand there is thus obtained a damping of the stream and on the other hand also a relatively constant powder-air stream-which makes it possible to coat uniformly with powder even considerably articulated surfaces of workpieces.

The distance of the deflection part may be adjustable relative to the exit orifice.

Furthermore, the distance of the breaker plate is likewise adjustable relative to the deflection part.

It is likewise possible, however, to proceed in such a way that the exit orifice and the deflection part are harmonized aerodynamically with one another as regards the surface formation so that it is possible to cause, at the deflection part, a deflection which influences the energy flux.

The surface formation in the curve can be harmonized aerodynamically with a blow-off angle. If one makes a shrewd choice of the curve of the breaker plate, it is possible to attain, for instance, an appropriate angle of outlet from the gun in the direction of the workpiece.

In this connection it is useful to mention that the diameter of the deflection part and of the breaker plate are of prime importance for the passage of the powderair mixture and for the angle of outlet.

Furthermore it is possible to adjust, through the handle of the gun, the deflection part as well as the breaker plate. As a matter of course, it is possible to proceed in such a manner that solely the breaker plate isadjusted through the handle of the gun whereas the deflection part is adjusted once at the beginning of the operation before making use of the gun.

As far as the shaping of the deflection part of the breaker plate is concerned, it may be convenient to adopt as a rule the circular form.

It is, of course, also possible to choose for the deflection part andfor the breaker plate, for example,'an oval or elliptical form for the purpose of producing a relatively broad stream.

In order to be able to change quickly the stream form, itis possible to proceed in such a way that the deflection part and the breaker plate can be exchanged as a coupled unit with a flick of the wrist.

As appears from an embodiment, the external border of the deflection part can be located even in the proximity of the breaker plate. This way of proceeding permits to produce varied stream forms as well as varied stream speeds in the direction of the workpiece.

It is advisable to coat, with plastics of the group of polytetrafluorethylenes or plastics of the group of copolymeres derived from tetrafluorethylene, hexafluorpropylenes or of similar groups, the parts which come in contact with powder, for instance the surfaces of the deflection plate and of the breaker plate or to make these parts directly of the aforementioned plastics.

Moreover, it is also possible to apply siliconized plastics for this purpose, as it is well known in the plastics technology for other applications.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings, which are schematic representations of the invention:

FIG. 1 is a schematic longitudinal. sectional view of the head of a powder spraying gun;

FIG. 2 is a plan view of the head of a powder spraying gun with a circular deflection part and a circular breaker plate;

FIG. 3 is a plan view of the powder spraying gun with an oval deflection part and an oval breaker plate; and

FIG. 4 is a schematic partial longitudinal sectional view of the head of a powder spraying gun wherein a stream of the powder-air mixture can emerge therefrom directly forwardly.

DESCRIPTION OF THE REFERRED EMBODIMENTS FIG. 1 represents an outlet or discharge tube of a powder spraying gun I, in which a powder-air mixture under pressure flows outwardly in the direction of arrow 2. There is placed at the outlet or exit orifice 3 a deflection part 4 which is mounted by means of the mounting piece 9, at the outlet orifice 3. The surface 14 of part 4 deflects the stream of the powder-air mixture substantially in the direction of arrow 5, so that the mixture impinges on the surface 6 of the breaker plate 7, which deflects the stream of the powder-air mixture in the direction of arrow 8 toward the workpiece 15. In the present case of FIG. 1, there is available a circular deflection part and a circular breaker plate.

Furthermore, it can be seen from FIG. 1 that the deflection part can be adjusted in the direction of arrow 13 whereas it is possible to render adjustable the breaker plate 7 in the direction of arrow 12.

FIG. 2 represents a plan view of a powder spraying gun to which are applied a circular deflection part 4 and a circular breaker plate 7.

FIG. 3 represents a plan view of a powder spraying gun to which are applied an oval deflection part and an oval breaker plate 11.

FIG. 4 represents a schematic partial section of a head of a special type where the adjustable deflection part 16 is provided with holes 17 which cooperate with corresponding holes in a fixed device 18, where it is possible to enlarge or reduce the passage orifices so that a selected part of the powder-air mixture can be discharged directly forward in the direction of arrow 20.

The holes 17 are discernible also in FIG. 2. It is possible to obtain in this way a combined conveying of powder to workpiece with the gun operating with deflection and/or in a straightforward manner.

The invention offers the additional advantage that, when operating in accordance with the suggested directives and applying an electrostatic electrode, it is possible to place the electrodes 21 of the high-tension part 22 further inwardly, for example on a level with the breaker plate 7 as is seen in FIG. 1. This will contribute to diminish the detonation-danger.

What is claimed is:

1. In a powder spraying gun including a discharge tube through which a powder-air stream flows under pressure for discharge through an exit orifice at the outer end of the tube, an improved discharge head comprising, in combination, a deflection part, for the powder-air stream, mounted on said discharge tube in axially outwardly spaced relation to said exit orifice and in the path of the discharged powder-air stream; said deflection part having a first deflection surface on which the powder-air stream impinges and which deflects the powder-air stream impinging thereon through an angle of substantially 180 to flow axially inwardly in surrounding relation to said discharge tube; and a breaker plate mounted on said discharge tube axially inwardly of said exit orifice and having a second deflecting surface on which the initially deflected powder-air stream impinges and which re-deflects the powder-air stream impinging thereon to flow axially outwardly, as a conically diverging spray, toward a workpiece to be coated.

2. An improved discharge head, as claimed in claim 1, in which the axially spaced relation of said deflection part to said exit orifice is adjustable.

3. An improved discharge head, as claimed in claim 1, in which said breaker plate is adjustable axially with respect to said deflection part.

4. An improved discharge head, as claimed in claim 1, in which the surface of said exit orifice and said first deflection surface are aerodynamically coordinated with each other to deflect the powder-air stream impinging on said first deflection surface through an angle of substantially 5. An improved discharge head, as claimed in claim 1, in which said first deflection surface is a curved surface having a curvature such as to deflect the powderair stream impinging thereon through an angle of substantially 180.

6. An improved discharge head, as claimed in claim 1, in which said deflection part and said breaker plate are circular in plan.

7. An improved discharge head, as claimed in claim 1, in which said deflection part and said breaker plate are substantially elliptical in plan.

8. An improved discharge head, as claimed in claim 1, in which said deflection part has an axially extending peripheral flange projecting into the proximity of said breaker plate.

9. An improved discharge head, as claimed in claim 1, in which those parts of said deflection part and said breaker plate which come in contact with the powder are formed of plastics of the group consisting of polytetrafluorethylenes and 'copolymers of tetrafluorethylene and hexafluorpropylenes.

10. An improved discharge head, as claimed in claim 1, in which those parts of said deflection part and said breaker plate which come in contact with the powder are formed of siliconized plastics.

11. An improved discharge head, as claimed in claim 1, in which said deflection part comprises two superposed plate portions each formed with apertures adjustable into alignment with each other by relative angular movement of the two plate portions to selectively control and block discharge of a portion of the powderair stream axially outwardly without deflection. 

1. In a powder spraying gun including a discharge tube through which a powder-air stream flows under pressure for discharge through an exit orifice at the outer end of the tube, an improved discharge head comprising, in combination, a deflection part, for the powder-air stream, mounted on said discharge tube in axially outwardly spaced relation to said exit orifice and in the path of the discharged powder-air stream; said deflection part having a first deflection surface on which the powder-air stream impinges and which deflects the powder-air stream impinging thereon through an angle of substantially 180* to flow axially inwardly in surrounding relation to said discharge tube; and a breaker plate mounted on said discharge tube axially inwardly of said exit orifice and having a second deflecting surface on which the initially deflected powder-air stream impinges and which redeflects the powder-air stream impinging thereon to flow axially outwardly, as a conically diverging spray, toward a workpiece to be coated.
 2. An improved discharge head, as claimed in claim 1, in which the axially spaced relation of said deflection part to said exit orifice is adjustable.
 3. An improved discharge head, as claimed in claim 1, in which said breaker plate is adjustable axially with respect to said deflection part.
 4. An improved discharge head, as claimed in claim 1, in which the surface of said exit orifice and said first deflection surface are aerodynamically coordinated with each other to deflect the powder-air stream impinging on said first deflection surface through an angle of substantially 180*.
 5. An improved discharge head, as claimed in claim 1, in which said first deflection surface is a curved surface having a curvature such as to deflect the powder-air stream impinging thereon through an angle of substantially 180*.
 6. An improved discharge head, as claimed in claim 1, in which said deflection part and said breaker plate are circular in plan.
 7. An improved discharge head, as claimed in claim 1, in which said deflection part and said breaker plate are substantially elliptical in plan.
 8. An improved discharge head, as claimed in claim 1, in which said deflection part has an axially extending peripheral flange projecting into the proximity of said breaker plate.
 9. An improved discharge head, as claimed in claim 1, in which those parts of said deflection part and said breaker plate which come in contact with the powder are formed of plastics of the group consisting of polytetrafluorethylenes and copolymers of tetrafluorethylene and hexafluorpropylenes.
 10. An improved discharge head, as claimed in claim 1, in which those parts of said deflection part and said breaker plate which come in contact with the powder are formed of siliconized plastics.
 11. An improved discharge head, as claimed in claim 1, in which said deflection part comprises two superposed plate portions each formed with apertures adjustable into alignment with each other by relative angular movement of the two plate portions to selectively control and block discharge of a portion of the powder-air stream axially outwardly without deflection. 